Come si cambia # 9/12 # nella forma più semplice?

To express a fraction in #color(blue)"simplest form"# we need to find a number, the largest is preferable, that divides into both 9 and 12.
In this case the largest number that divides into both is 3.

Now we divide 9 and 12 by 3

#rArr9/12=(9÷3)/(12÷3)=3/4" in simplest form"#

Usually, the task of dividing both numbers by 3 is performed mentally, stroking out the number and replacing it by the value remaining after division.This is called #color(red)"cancelling"#

#rArr(cancel(9)^3)/(cancel(12)^4)=3/4#